Portable devices such as smart phones, navigation units, tablet personal computers, and the like are generally equipped with an emissive color display, i.e., a color liquid crystal display (LCD), light emitting diode (LED) display, and organic LED (OLED) display. Emissive displays offer excellent indoor viewing experience but are difficult to view when used outdoors, especially under direct sunlight. Devices with emissive display also consume more energy, requiring more frequent battery charging.
In contrast, passive displays, also referred to as reflective displays such as electronic paper displays, offer improved readability for both indoor and outdoor applications. Passive displays rely on reflected light for viewing and consume much less energy due to their inherent bistability. This type of display is widely adapted in various e-book readers available in the marketplace. Examples include displays using electronic ink or rotating bi-colored beads. To take the advantages of both emissive and passive displays, integrated hybrid LCD/electronic paper displays have been proposed. Although the integrated hybrid display offers some advantages over conventional emissive displays, it also suffers from several shortcomings. For example, prior attempts to create a hybrid display also require complicated and costly electronic design for controlling both displays. Further, the viewability of the emissive display in the integrated hybrid design described above is decreased.